<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        
    </style>
</head>
<body>
    
</body>
<script>
    // console.log( isNaN(NaN) );
    // console.log( isNaN("hello") );
    // console.log( isNaN("365") );
    // var a = NaN;
    // console.log( NaN === NaN )
    // console.log( NaN == NaN )
    // console.log( a == a )


    // console.log(Number(undefined))
    // console.log(Number(null))
    // console.log(Number(NaN))

    // console.log(Boolean(undefined))
    // console.log(Boolean(null))
    // console.log(Boolean(NaN))

    // console.log( undefined == null )
    // console.log( undefined == NaN )
    // console.log( null == NaN )

    // console.log(undefined == false)
    // console.log(null == false)
    // console.log(NaN == false)

    // console.log(undefined == true)
    // console.log(null == true)
    // console.log(NaN == true)

    // console.log(undefined == 0)
    // console.log(null == 0)
    // console.log(NaN == 0)

    // // 看个热闹
    // console.log(Object.prototype.toString.call({}))
    // console.log(Object.prototype.toString.call([]))
    // console.log(Object.prototype.toString.call(""))
    // console.log(Object.prototype.toString.call(true))
    // console.log(Object.prototype.toString.call(function(){}))
    // console.log(Object.prototype.toString.call(undefined))
    // console.log(Object.prototype.toString.call(null))
    // console.log(Object.prototype.toString.call(NaN))
    // console.log(Object.prototype.toString.call(2123))


    console.log(1+1)
    
    console.log(0.1+0.1)

    console.log(0.1+0.2)
    console.log(0.1+0.3)
    console.log(0.1+0.4)
    console.log(0.1+0.5)
    console.log(0.1+0.6)
    console.log(0.1+0.7)

    // 二进制
    var a = 0.1+0.7;
    console.log(parseFloat(a.toFixed(1)));
    

</script>
</html>